Interactions between monocot leaf traits, extinction risk, and genome size

Alarming rates of plant biodiversity loss are being observed today, such as the roughly 45% of angiosperm species threatened with extinction. Currently the leading threat to plant biodiversity is land use change from human activity, although climate change is predicted to increasingly threaten plant species diversity over the next century. Leaf traits can dynamically respond to environmental change and so their analysis can reveal important trends in plant response to ongoing environmental changes. A link between genome size and extinction risk has been noted in angiosperms where herbaceous angiosperms with a large genome size have an increased risk of extinction in comparison to species with small genomes. Genome size determines minimum cell size available to a plant species thereby impacting bottom-up physiological processes and can determine leaf traits. The question remains, how do leaf traits, genome size, and extinction risk interact together? Monocot species have the largest range in genome size of all major angiosperm lineages. Monocot species from around the globe with both a Red List extinction risk assessment and a genome size measurement were selected for leaf trait analysis using specimens from Herbarium of the Royal Botanic Gardens, Kew. Of these species, 623 were selected for detailed macroscopic and microscopic leaf trait analysis. Species with an increased risk of extinction and larger genomes were significantly more likely to be petiolate, have a non-simple organisation, non-linear leaf laminar shape, lobation, and teeth. They were also significantly more likely to have larger stomata in terms of guard cell length and guard cell width, and a lower stomatal density. The stomatal traits showed the strongest relationship with both extinction risk and genome size, potentially offering a new lens through which to predict current plant species extinctions and examine the fossil record.

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University of Galway

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CC BY-NC-ND

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University of Galway Theses (Research Masters Theses)